Electrothermal oil treatment



p 1933- F. w. SULLIVAN, JR 1,927,074

ELECTROTHERMAL OIL TREATMENT Filed Oct. 28, 1931 a FredarizkW S UJMNQ/h.J'r'.

By .B w

Patented Sept. 19, 1933 UNITED STATES PATENT OFIQE signor to StandardOil Company, Chicago, 111., a corporation of Indiana Application October28,

11 Claims.

This invention relates to an electrothermal prcoess for treating oilsand it pertains more particularly to an improved method and means forconverting heavy petroleum hydrocarbons into lighter hydrocarbons, suchas gasoline.

The object of my invention is to provide a system whereby the yield ofgasoline from high boiling petroleum hydrocarbons may be increased andthe yield of tar and gases may be decreased, thus increasing theefficiency of the cracking process. A further object is to provide an improved method and means for supplying the last increment of heat intopetroleum hydrocarbons in a cracking process so that the heater may beoperated at lower temperatures and the factor of safety therebyincreased. A further object is to electrically activate hydrocarbongases whereby they may be chemically combined or utilized by heavyhydrocarbons in a cracking process for the production of light oils,such as gasoline. A further object is to provide an improved stable,high antiknock gasoline. Other objects will be apparent from thefollowing detailed description.

In practicing my invention I pass residual gases from a cracking processthrough an electrical arc whereby they are heated to a temperature ofbetween 1200 and 1500 F. and partly converted into activated hydrogen.The temperature in the arc is, of course, 3000 to 7000 F. and atthesetemperatures the hydrogen-containing gases are broken down and partiallyconverted into activated hydrogen. A sufiicient volume of gas is usuallyintroduced around the electrodes, however, to maintain a temperature inchamber of about 1500 F. I inject these hot activated gases intohydrocarbons entering the soaking drum of the cracking system. Thetemperature of the hydrocarbons is thereby raised from about 800 to 925F. The tendency to form tar or coke is reduced by the presence of theactivated hydrogen which is obtained from the waste gases of the system.The invention will be more clearly understood from the description of apreferred embodiment which is illustrated inthe accompanying drawingwherein- Figure 1 is a diagrammatic elevation partly in section of myimproved system,

Figure 2 is a detailed section showing a preferred form of an electricarc heater,

Figure 3 is a section taken along the lines 3-3 of Figure 2.

Figure 4 is a horizontal section of another embodiment of my improvedelectric arc heater.

The cracking system generally is along the lines of commercial vaporphase cracking units 1931. Serial No. 571,640

now in use. The heavy petroleum hydrocarbons which may be gas oil,naphtha bottoms, reduced crude, or other charging stock is introduced bypipe 10 into the tubes of pipe still 11. The exact routing of the oilthrough the pipe still forms no part of the present invention and it isonly essential that the oil be heated to a temperature of about 850 F.without material coke deposition and without too great a pressure drop.The last part of the pipe still heating is conveniently accomplished inthe top tubes of the convection section from which the hot hydrocarbonsare conducted by pipe 12 into the base of soaking drum 13.

The soaking drum, which is well insulated, is

normally operated under a pressure of about 300 pounds. At its base Iprovide a tar draw-off pipe 14 containing a suitable valve 15. Vaporsfrom the top of the soaking drum are withdrawn through pipe 16, passedthrough reducing valve 17 and introduced into preliminary fractionatingtower 18 which is equipped with suitable baffles, cooling coils, etc. Alight tar is drawn from the base of this tower through pipe 19 and valve20. Gases and vapors are conducted by pipe 21 from the top of tower 18to rectifier 22 which is also equipped with suitable bubble plates,cooling means, reflux means, stripping means, etc. The heavy ends fromthe base of tower 22 are withdrawn through pipe 23, pump 24, and pipe 25which leads back to the pipe still. This cycle stock is diagrammaticallyshown entering the pipe still with fresh feed, but it is understood thatcycle stock may be introduced into the pipe still at any suitable point,preferably where the temperature of the oil in the coils is equal to thetemperature of the cycle stock. Light hydrocarbon gases and vaporsleaving the top of tower 22 by pipe 26 are partially condensedin coil 27and are introduced by pipe 28 into separator 29, condensate beingwithdrawn through cooling coil 30 and the uncondensed gases beingdischarged from the top of the separator through pipe 31. The residualgases in pipe 31 contain some methane and ethane, hydrogen, lightolefins, etc., the mixture being similar to what is ordinarily termedrefinery gases. These gases are conducted by pipe 32 to are heater 3'7so that they can be further utilized in the manufacture of gasoline.

In order to prevent a large amount of gas from accumulating in thesystem I provide a discharge pipe 33 for bleeding out small amounts ofgases when their volume is unduly increased. On the other hand, it maybe desirable to add refinery gases from other parts of the plant or toinject hydrogen into the system through pipe 34. These gases, whichcontain hydrogen in the free or combined state, are compressed bycompressor and introduced by means of pipe 36 into electric arc heater37. The gas is preferably divided and introduced into the heater bymeans of two inlet nozzles 38 and 39, the amount of gas in each nozzlebeing regulated by valves in the respective connecting arms 38A and 39A.Both nozzles terminate in a chamber 40 and are arranged with theirdischarge ends relatively close together and at an angle to each other.Tungsten electrodes 41 and 42 extend through the respective nozzles.Electrode 41 is insulated from nozzle 38 by packing material 43 andseparator 44, both of which are composed of suitable insulatingmaterial. Likewise, electrode 42 is insulated from nozzle 39 by means ofpacking material 45 and separator 46. Electrode 41 may be moved inwardlyor outwardly by means of regulating handle 47 and electrode 42 may besimilarly regulated by handle 48. These electrodes are connected byconductors 49 and 50 to a suitable power source 51 which is designed tooperate at voltages of from 220 to 440 and to deliver sufficient currentto heat the gases to about 1200-1500 F. and to activate the hydrogen. Inthe accompanying drawing, the electrode mounting and the nozzles havebeen shown more or less diagrammatically, but it is understood that anysuitable means may be used whereby these nozzles may withstand crackingpressures and whereby the electrodes may be insulated from the sides ofthe nozzles.

The structure of the arc chamber will be best understood by reference toFigures 2 and 3. A high temperature alloy steel chamber 52 is Welded tothe side of the soaking drum 13 adjacent the discharge of pipe 12. It isprotected on its inner side by a refractory material 53, such as fireclay, and it is protected on its outside by suitable insulating material54, which insulating material also surrounds the soaking drum and hotpipes. The chamber preferably opens directly into the soaking drum andis disposed at a slight angle to pipe 12. I may, however, use themodification shown in Figure 4, wherein the chamber is mounted directlyabove pipe 12 and does not directly communicate with the soaking drum.

The operation of my invention is as follows: The charging stockintroduced by pipe 10 is heated to a temperature of about 850 F. in pipestill -11 and is then discharged through pipe 12 into soaking drum 13 ata pressure of about 150-300 pounds. In orde that the soaking drum mayoperate under vapor phase conditions I prefer to increase thetemperature of the charging stock to 925 F. It is difiicult to obtainthese temperatures in a pipe heater because even high temperature alloytubes often fail at these temperatures and pressures. 'I reduce thedanger and facilitate the operation of the heater by supplying the lastincrement of heat by means of electrode heater 37.

Refinery gases from pipe 36 are fed into chamber 40 around electrodes 41and 42, so that the gases act as a cooling medium therefor. The arc isadjusted to give a current suflicient to heat the hydrogen containinggases to a temperature of about 1200 to 1500 F. so that the mixture ofthese gases with heated charging stock may give a resultant temperatureof about 925 F. or above. It should be noted that the charging stockdoes not pass directly through the are or in close enough proximitythereto to become decomposed. At least a part of the hydrocarbon gaseswhich are introduced around the electrodes are decomposed in the arc toform hydrogen small amounts of free carbon and acetylene. Under theseconditions part of the hydrogen is activated and/or converted intoatomic hydrogen. This electrically activated hydrogen is unusuallyeffective in converting the hot charging stock into gasoline and inminimizing the formation of coke. I do not limit myself to any theory orexplanation of these phenomena, but it appears that the introduction ofelectrically activated gases and hydrogen into the hydrocarbon vaporsundergoing thermal dissociation prevents polymerization and formation ofcoke and undesirable tarry residues.

The carbon produced in the arc and the small amount of heavy tar whichmay form in soaking drum 13 are periodically or continuously withdrawntherefrom through pipe 14. The light reaction products pass throughexpansion valve 17 into fractionating or rectifier towers l8 and 22.Light tar from pipe 19 may, in some cases, be recirculated through thesystem as cycle stock or it may be withdrawn for other purposes.Fractionating tower 22 is preferably at about atmospheric pressure sothat both the cycle stock from this tower and the gases from separatingchamber 29 must be compressed before they are reintroduced into thesystem.

The apparatus illustrated in Figures 1 to 3 is advantageous from thestandpoint of carbon deposition because the turbulent action of the hotgases tends to sweep this deposit into the soaking drum where it issuspended in heavy tar and withdrawn. The modification in Figure 4 maybe employed in a coil cracking system wherein sufiicient soaking of thevapors is provided by additional insulated pipe coils usually employinglarge diameter pipes.

While I have described in detail a preferred embodiment of my inventionit is to be understood that I do not limit myself to said details exceptas defined by the following claims.

I claim:

1. In apparatus of the class described for converting heavy hydrocarbonsinto gasoline by the combined process of pyrolitic cracking anddestructive hydrogenation, a pipe still for heating charging stock toabove 800 R, an electric arc heater for heating hydrogen containinggases to a temperature of about 1200 to 1500 E., and means for mixingsaid heated gases with said heated charging stock whereby a resultingtemperature of about 925 is obtained.

2. In apparatus of the class described for converting heavy hydrocarbonsinto gasoline, an insulated soaking drum adapted to withstand a pressureof about 150300 pounds per square inch, a pipe heater for elevating thetemperature of said hydrocarbons, an electric arc heater for adding thelast increment of heat thereto, means for passing hydrogen-con aininggases through said arc heater and means for subsequently mixing saidgases with said heated heavy hydrocarbons and for introducing them intosaid soaking drum.

3. In apparatus of the class described for converting 'heavyhydrocarbons into gasoline, an insulated soaking drum adapted towithstand high pressures, means for heating said heavy hydrocarbons andintroducing theminto said soaking drum, means for separately recoveringheavy hydrocarbons, light hydrocarbons and hydrogencontaining gases fromthe products of said soaking drum, an electric arc, means for passing aportion of said hydrogen-containing gases through said electric arc, andmeans for subsequently mixing said gases with the heated heavyhydrocarbons entering said soaking drum.

4. In apparatus of the class described for converting heavy hydrocarbonsinto gasoline, means for heating saidhydrocarbons to crackingtemperature, a passage conduit leading from said heating means, an arcchamber adjacent to said discharge conduit and communicating therewith,arc electrodes in said chamber, means for mounting said electrodeswhereby atleast one of them is insulated from the system and from theother electrodes, and means for introducing a hydrogen-containing gasinto said chamber to regulate the temperature thereof and to combinewith the heated hydrocarbons adjacent thereto.

5. In apparatus of the class described for converting heavy hydrocarbonsinto gasoline, a reaction drum, an arc chamber adjacent thereto andcommunicating'therewith, arc electrodes in said chamber, means forintroducing a hydrogen-containing gas into said arc chamber for coolingsaid are electrodes, regulating the temperature in said chambers andfinally regulating the temperature in said reaction drum.

6. In apparatus of the class described, a reaction chamber, an arcelectrode adjacent to said chamber and communicating therewith at apoint spaced from the bottom thereof, means for withdrawing liquids andliquid suspensions from the bottom of said chamber, means for removinggases and vapors from the top of said chamber,

means for introducing a heated hydrocarbon into saidchamber, and meansfor introducing a hydrocarbon gas into said are chamber so that thecarbon which is formed by the arc may be suspended in heated petroleumliquid and withdrawn from the base of said chamber.

'7. In apparatus of the class described, an arc chamber, two nozzlesextending into said are chamber and inclined toward each other wherebythe gases from said nozzles impinge in said are chamber, arc electrodesextending through said nozzles, means for insulating at least one areelectrode from theother and from the system, and means for introducinggases in regulated amountsinto said nozzles whereby the gases flowaround said electrodes to cool the same and whereby the gases impinge atthe point of the arc so that the reaction products of the are are swepttherefrom.

8. In apparatus of the duit, an arc chamber adjacent said conduit, arcelectrodes in said chamber, means for introducing a cooling gas aroundsaid electrodes whereby part of said gases are heated in the arc to atemperature of 3000 to 7000 F. and the temperature in the chamber ismaintained at about 1200 to 1500 F., the gases from the arc chamberbeing introduced into said conduit to regulate the temperature ofliquids flowing therein.

9. The combination of claim 8 wherein heated hydrocarbons are in saidconduit and hydrocarbon gas is passed through saidarc chamber so that apart of the hydrocarbon gas will be converted into activated hydrogenwhich, on introduction into the conduit, elevates the temperaturethereof and reacts therewith.

10. In apparatus of the class described, a pipe still, a soaking drum,means for passing a hydrocarbon oil through said pipe still andintroducing it into said soaking drum, an electric arc adjacent saidconduit and communicating therewith, means for removing liquids andliquid suspensions from the base of said soaking drum, means forseparating gasoline and hydrocarbon gases from the reaction products ofthe soaking drum, and means for returning said hydrocarbon gases to saidsoaking drum through said arc.

11. The method of vconverting heavy hydrocarbons into gasoline whichcomprises heating said hydrocarbon to a temperature of about 800 F. in aclosed conduit, heating a light hydrocarbon gas in an electric arcwhereby it is decomposed, activated and is raised to a high temperature,and combining the hot reaction products of the electric arc with theheated hydrocarbon in the conduit so that the temperature of thehydrocarbon in the conduit is raised to about 925 F. and the reactionproducts of the arc combine with the heated hydrocarbon.

FREDERICK W. SULLIVAN, JR.

class described, a eon-

